National Veterinary Services Laboratories 

Bluetongue Virus Antibody

Proficiency Test Summary 

1. Composition of proficiency test panel: The bluetongue (BT) virus antibody panel consists

of twenty 0.6 ml samples of domestic ruminant (bovine or ovine) serum. The panel contains 

negative, weak positive and strong positive samples, and includes blind duplicates. The samples 

are labeled with the test acronym and calendar year (e.g., BT 2013), a panel set number (e.g. Set 

65), and a Sample number (Sample 1 through 20). The samples are scrambled between sets. 

2. Cost of proficiency test: Click here to view current NVSL Catalog of reagents. Additional 

information on diagnostic reagents, including ordering, payments, shipping details and fees, is 

located at www.aphis.usda.gov/nvsl. Then click on the Reagents and Proficiency Tests link.

3. Storage conditions: Short term (up to 7 days) store at 4° ± 2° C. Long term (over 7 days) 

store at or below -20° C in a non-frost free freezer.

4. Sample preparation/selection criteria: Samples with high, medium, and low concentrations 

of BT virus antibody are chosen for incorporation into the panel. Antibody levels arise from 

naturally acquired infections. In order to provide a range of reactions, some bluetongue 

antibody-positive samples are diluted in bluetongue antibody-negative fetal bovine serum. Each 

panel member is tested at least five (5) times using licensed test kits by a minimum of two NVSL 

technicians. Note: NVSL is an OIE reference laboratory for bluetongue. 

5. Panel quality control: Samples are monitored for stability and reproducibility. The stability 

of the panel is a determination that normal shipping and handling conditions do not change the 

end values of the panel. Panel sets of each lot of proficiency panels are used to confirm stability 

after final preparation. 

6. Timing of the proficiency test distribution and data collection: The BT proficiency test is 

administered annually, customarily in the month of May. 

7. Test method: Performance and interpretation of the BT proficiency should be conducted 

using USDA licensed kit and following manufacturer’s directions. 

Bluetongue AGID and ELISA tests at NVSL are ISO17025 accredited.

8. Submitting test results: Participating laboratories are required to have data submitted for 

scoring no more than four (4) weeks after panel distribution. Results are reported to the NVSL 

by fax, email, or mail. One set of results is reported from each laboratory, along with test kit 

information. 

9. Scoring of individual panel samples: The BT proficiency test is an annual test of 

laboratories approved to conduct official BT testing. Procedures for approved laboratories are 

described in VS Memorandum 555.8. Official BT tests are defined as those tests conducted for 

Revision: April 2013
the purpose of certifying animals or products for international movement. One result for each 

sample is reported per laboratory. Sample results are reported as positive or negative. 

10. Laboratory pass/fail criteria: The final score is based on the identification of positive and 

negative samples. An NVSL/CVB statistician is consulted to determine the appropriate pass/fail 

cutoff. 

11. Reporting laboratory test scores: Results for each laboratory are reported to the respective

laboratory director and to the appropriate AVIC for the laboratory’s location. Reports include 

individual laboratory results for each sample as well as summary results of participants in the 

proficiency test. Results are compiled and reported within 30-60 days of the due date for receipt 

of participants’ results.

12. Remedial actions required for failing laboratories: Laboratories that do not pass on the 

first attempt are given the option of purchasing a second panel for a retest. Laboratories that fail 

the proficiency test are encouraged to contact subject matter experts at NVSL for discussion of 

methods and resolution of potential areas of concern. If a failing laboratory declines to take, or 

does not pass, the retest the laboratory is recommended for removal from the list of approved 

laboratories for official BT testing. Laboratories that are removed from the approved list are 

advised that retraining at NVSL is needed for reconsideration of laboratory approval. 

All appeals are documented and evaluated on a case-by-case basis.

13. Special requirements: Licensed kits for diagnostic testing for BT antibody are 

commercially available to veterinary diagnostic laboratories. A list of laboratories approved for 

official (export) BT testing is maintained by APHIS/VS. As of 2013, approximately 60 

laboratories are approved for official BT serology testing. 

The current list of approved laboratories can be found at: 

http://www.aphis.usda.gov/animal_health/lab_info_services/approved_labs.shtml

International requests for the BT proficiency panel are considered on a case-by-case basis and 

must follow applicable authorization and permit requirements. 

Revision: April 2013